Re: [PATCH v5 3/3] arm64,ppc64le/kdump: pass dm-crypt keys to kdump kernel

Coiby Xu
2026-04-02T01:50:39Z

On Mon, Mar 30, 2026 at 06:44:15AM -0500, Rob Herring wrote:
>On Wed, Feb 25, 2026 at 12:04 AM Coiby Xu <coxu@redhat.com> wrote:
>>
>> CONFIG_CRASH_DM_CRYPT has been introduced to support LUKS-encrypted
>> device dump target by addressing two challenges [1],
>> - Kdump kernel may not be able to decrypt the LUKS partition. For some
>> machines, a system administrator may not have a chance to enter the
>> password to decrypt the device in kdump initramfs after the 1st kernel
>> crashes
>>
>> - LUKS2 by default use the memory-hard Argon2 key derivation function
>> which is quite memory-consuming compared to the limited memory reserved
>> for kdump.
>>
>> To also enable this feature for ARM64 and PowerPC, the missing piece is
>> to let the kdump kernel know where to find the dm-crypt keys which are
>> randomly stored in memory reserved for kdump. Introduce a new device
>> tree property dmcryptkeys [2] as similar to elfcorehdr to pass the
>> memory address of the stored info of dm-crypt keys to the kdump kernel.
>> Since this property is only needed by the kdump kernel, it won't be
>> exposed to user space.
>>
>> [1] https://lore.kernel.org/all/20250502011246.99238-1-coxu@redhat.com/
>> [2] https://github.com/devicetree-org/dt-schema/pull/181
>>
>> Cc: Arnaud Lefebvre <arnaud.lefebvre@clever-cloud.com>
>> Cc: Baoquan he <bhe@redhat.com>
>> Cc: Dave Young <dyoung@redhat.com>
>> Cc: Kairui Song <ryncsn@gmail.com>
>> Cc: Pingfan Liu <kernelfans@gmail.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Krzysztof Kozlowski <krzk@kernel.org>
>> Cc: Rob Herring <robh@kernel.org>
>> Cc: Thomas Staudt <tstaudt@de.ibm.com>
>> Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
>> Signed-off-by: Coiby Xu <coxu@redhat.com>
>> ---
>> arch/arm64/kernel/machine_kexec_file.c | 4 ++++
>> arch/powerpc/kexec/elf_64.c | 4 ++++
>> drivers/of/fdt.c | 21 +++++++++++++++++++++
>> drivers/of/kexec.c | 19 +++++++++++++++++++
>> 4 files changed, 48 insertions(+)
>
>Acked-by: Rob Herring (Arm) <robh@kernel.org>

Hi Rob,

Thanks for acknowledging this device tree patch and also merging the
dt-schema PR!

--
Best regards,
Coiby